package work.darren;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.net.ServerSocket;
import java.net.Socket;

public class RpcFramework {
    public static void export(Object service, Class interfaceClazz, int port) throws Exception {
        if (service == null) {
            throw new IllegalAccessException("service instance == null");
        }
        if (port < 0 || port > 65535) {
            throw new IllegalAccessException("Invalid port " + port);
        }
        System.out.println("Export service " + service.getClass().getName() + " on port " + port);

        ServerSocket server = new ServerSocket(port);
        for (; ; ) {
            Socket socket = server.accept();
            new Thread(() -> {
                try (ObjectInputStream input = new ObjectInputStream(socket.getInputStream());
                     ObjectOutputStream output = new ObjectOutputStream(socket.getOutputStream())) {
                    String interfaceName = input.readUTF();
                    String methodName = input.readUTF();
                    Class<?>[] parameterTypes = (Class<?>[]) input.readObject();
                    Object[] arguments = (Object[]) input.readObject();
                    try {
                        if (!interfaceName.equals(interfaceClazz.getName())) {
                            throw new IllegalAccessException("Interface wrong, export:" + interfaceClazz + " refer:" + interfaceName);
                        }
                        Method method = service.getClass().getMethod(methodName, parameterTypes);
                        Object result = method.invoke(service, arguments);
                        output.writeObject(result);
                    } catch (Throwable t) {
                        output.writeObject(t);
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }).start();

        }
    }

    @SuppressWarnings("unchecked")
    public static <T> T refer(Class<T> interfaceClass, String host, int port) throws Exception {
        if (interfaceClass == null) {
            throw new IllegalAccessException("Interface class == null");
        }
        if (!interfaceClass.isInterface()) {
            throw new IllegalAccessException(interfaceClass.getName() + " must be interface");
        }
        if (host == null || host.length() == 0) {
            throw new IllegalAccessException("host == null");
        }
        if (port <= 0 || port > 65535) {
            throw new IllegalAccessException("Invalid port " + port);
        }
        System.out.println("Get remote service " + interfaceClass.getName() + " from server " + host + ":" + port);
        return (T) Proxy.newProxyInstance(interfaceClass.getClassLoader(), new Class<?>[]{interfaceClass},
                (proxy, method, args) -> {
                    try (Socket socket = new Socket(host, port);
                         ObjectOutputStream output = new ObjectOutputStream(socket.getOutputStream());
                         ObjectInputStream input = new ObjectInputStream(socket.getInputStream())) {
                        output.writeUTF(interfaceClass.getName());
                        output.writeUTF(method.getName());
                        output.writeObject(method.getParameterTypes());
                        output.writeObject(args);
                        Object result = input.readObject();
                        if (result instanceof Throwable) {
                            throw (Throwable) result;
                        }
                        return result;
                    }
                });
    }
}
